The extraordinary revelation this week that the Internal Revenue Service targeted tea party groups for more aggressive enforcement highlights exactly why caution is needed in any response to the much-vilified Supreme Court decision in Citizens United v. FEC.

It also shows how all Americans, from the most liberal to the most conservative, should closely guard their First Amendment rights, and why giving the government too much power to limit political speech will inevitably result in selective enforcement against unpopular groups.

To the agency's credit, Lois Lerner, a senior official at the IRS, apologized on Friday for these unconstitutional practices, which are as unseemly as the Bush administration's targeting of the NAACP and the House of Representatives' defunding of Planned Parenthood on purely political grounds.

Lerner said that career IRS staff who were reviewing applicants for tax-exempt status took a harder look at applications with "tea party" or "patriot" in their names.